This invention relates to a prosthetic device. Specifically it relates to a prosthetic hip joint for use with a prosthetic upper and lower limb to replace an entire lower limb and the associated hip joint.
Upon removal of a portion of the pelvis of a humam, replacement of the hip joint becomes a necessity if the patient is to resume walking. It is to be understood that removal of the upper and lower limb for medical reasons caused either by trauma or disease results in concurrent removal of the musculature of the leg. If there is a residual portion of the upper limb remaining the patient retains a degree of control over the swing of a prosthesis. However should it become necessary to remove the hip joint and a portion of the pelvis the patient has no muscular ability to swing an artificial limb and thus achieve any degree of ambulation without swinging his torso. Furthermore control of the knee is lost by loss of the muscle structure of the upper and lower limb.
If an operative knee joint is to be included in a prosthesis for a complete limb, articulation of that replacement knee joint is usually accomplished by the swing motion of the leg. Thus as the patient swings the residual upper limb forward the replacement knee may flex due to the inertia of the foot. When the residual limb is stopped anterior of the body the inertia of the lower limb now carries the lower limb forward thus extending the knee so that the entire prosthesis is in generally a straight line at the time heel contact occurs. If the amputee does not have a residual limb so that muscle structure does not remain to swing the residual limb and an associated prosthesis forward, either the body must be utilized to swing the prosthesis or some mechanical structure must accomplish the swing.
In existing prosthetic hip replacement structures for use with an artificial limb, the emphasis has been on biasing the artificial limb to remain in the frontal plane of the body. With this approach the amputee has a second burden placed on him in the event of a complete hip replacement. In addition to having to swing the prosthesis by body muscle, the amputee must also overcome the biasing of the prosthesis to remain in the frontal plane. Prostheses of this type have been necessitated generally because of the knee structure. Prosthetic knees, in the past, were not designed to shift from an unlocked (flexing) to a locked (extended) condition during walking by the patient. This limitation has recently been overcome by the introducton of a weight activated knee joint. This knee joint is available from the Otto Bock Company of West Germany and is designed such that upon heel contact of an associated prosthetic foot the force applied to the upper limb through the knee joint locks the knee. As the prosthesis passes through mid-stance the knee joint mechanically unlocks yet remains bimechanically locked to the point of heel-off at which time the knee is free to flex.
With the advent of this new knee joint, the knee joint limitation imposed upon a prosthetist in designing a full leg replacement including a hip joint is largely overcome. Specifically the prosthetist no longer has to worry about the knee flexing at heel contact. Nevertheless the prosthetic equipment manufacturers have continued to provide the extension biased hip joints (described above) which bias the prosthetic members to the frontal plane of the body. Tests with patients utilizing such structures indicate the energy requirements to operate extension biased hips and the associated lower limb were approximately twice the normal energy requirements.
It was with this background that the flexion biased prosthesis described herein was developed. Specifically the flexion biased prosthesis described herein overcomes the major drawback of the commonly used extension biased hip joint in its primary objective of reducing energy requirements to an amputee to a minimum level.
It is a further object of the present invention to provide a lightweight easily operable structure for complete lower limb replacement.
It is also an object of this invention to provide a prosthesis which may be adjusted by the user for different conditions. Other objects will become apparent from a study of the accompanying drawings and the following specification.